Character strings to natural language processing in information retrieval

The levels-of-processing theory proposes that there are many ways to process and code information. The level of processing adopted will determine the quality of the representation used to store the information in the computer memory or storage. The levels-of-processing applied in information retrieval can be classified as follows: string processing, morphological processing, syntactic processing and semantic processing. These level-of-processing are imbedded into various models of information retrieval. Conventional information retrieval models, such as Boolean and vector space models rely on an extensive use of keywords, as independent strings, and their frequencies in storing and retrieving information. Thus string processing and morphological processing are mainly adopted in these models. It is believed that such an approach has reached its upper limit of retrieval effectiveness, and therefore, new approaches should be investigated for the development of future systems that will be more effective. With current advances in programming languages and techniques, natural language processing and understanding, and generally in the fields of artificial intelligence and cognitive science, there are now attempts made to include knowledge representation and linguistic processing into information retrieval systems. We also focus our research on the application of certain techniques on specific languages. Besides English, we focus the application of certain techniques especially on Malay. In this paper we will highlight some of the research done in the area of information retrieval at the various levels of processing, and also expound the current research we are doing and the future direction that we would like to undertake.